The aim of this proposal is to develop an inexpensive, handheld device that can be used by primary caregivers (such as general practitioners, internists, and endocrinologists) and in screening settings to reliably screen at-risk diabetics for retinopathy and provide immediate results. This device has the potential to save the sight of thousands of diabetics who have undetected diabetic retinopathy by identifying their condition and allowing timely referral to an ophthalmologist for evaluation and treatment. The device works by measuring the implicit time of the 30 Hz flicker electroretinogram, which has been repeatedly shown to correlate well with severity of diabetic retinopathy. Because the device measures implicit time, it will record from skin electrodes placed near the eye. The device will automatically detect good electrode contact. Pupil size will be automatically measured and the light intensity will be adjusted to provide an optimal retinal stimulus. Proven algorithms will be used to measure the implicit time from the elicited waveform, and the results will be displayed to the caregiver along with an estimate of the reliability of the measurement. LKC Technologies already possesses most of the technologies necessary to develop this device, notably compact low noise, saturation-resistant digital patient amplifiers, sophisticated circuitry for controlling the light output of LEDs, and proven analysis algorithms. In Phase I, a proof-of-principle prototype was developed by modifying an LKC UTAS visual electrophysiology system with an off-the shelf pupillometer and custom software. Data were recorded to assess the robustness of the algorithms for measuring signal quality and extracting implicit time and to determine optimal stimulus parameters. In Phase II, a complete handheld prototype instrument will be constructed, and data will be collected from a large population of diabetics in a screening environment to demonstrate the effectiveness of the device. An additional study will recruit patients with varying levels of diabetic retinopathy to evaluate the usefulness of the device over a wide range of retinopathy. PUBLIC HEALTH RELEVANCE: Relevance Twenty-four million people in the United States suffer from diabetes;five million of them have some degree of diabetic retinopathy - the leading cause of blindness in working-age adults. Although $493 million is expended annually for healthcare related to diabetic retinopathy, another 18,000 people in the United States will go blind this year from the disease. Many diabetics do not know that they have diabetic retinopathy because there is no quick, easy, inexpensive, and widely available screening method. This project proposes to develop a compact, easy-to-use, cost-effective device that would allow diabetics at risk for retinopathy to be evaluated quickly and inexpensively in primary care or screening environments and referred for treatment to preserve their sight.